1. Field of the Invention
This invention relates generally to a dental treatment chair assembly and more particularly to a dental treatment chair assembly including a unit table having various instruments attached thereto in combination with an arm mechanism, the assembly being designed to meet the convenience of a doctor (dentist) and a nurse (his assistant) in their treatment activities by enlarging the range of operation of the arm mechanism.
2. Prior Art
Japanese Patent Application Open to Public Inspection No. 37297/1975 disclosed a device for giving both to a doctor and to a nurse convenient access to the unit table and removing inconvenience due to positioning of the arm mechanism over the head (belly) of a patient in a crossing relation by fixing the arm mechanism adapted to elevatably and rotatably support the unit table to a base below the backrest of a dental chair so as to permit the free rotation of the arm mechanism, and the device has so far provided convenience in its own way. But this prior art device permits only arcuate movement around one shaft with respect to the base such that the device provides the range of rotation and range of elevation by pivotally jointed segment of each arm, but nevertheless the device does not make it possible for the dentist and the nurses to locate the unit table in a position suitable for them. For example, when the dentist moved from a former position to a new treatment position, and when he desired to move the unit table in the former position horizontally to the new position in exactly the state in which it formerly was, the prior art device made it necessary to position the unit table in the desired position by reactivating the pivotally jointed segments of the arm mechanism.